Yi Zhuangfang (依庄防) has been immersed in the story of rubber in Xishuangbanna for more than half her life. Her parents own a small rubber plantation and after earning a bachelor's degree in physical geography from Sun Yat-sen University in Guangzhou she returned to Yunnan to begin her PhD studies at Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, under the supervision of tropical ecologist, Dr Charles H Cannon.

Growing rubber as a cash crop has come as an economic blessing to many farmers in southern Yunnan. But along with money have come several little-discussed environmental and societal problems for many of the area's Dai minority smallholders.

Yi Zhuangfang (依庄防) has been immersed in the story of rubber in Xishuangbanna for more than half her life. Her parents own a small rubber plantation and after earning a bachelor's degree in physical geography from Sun Yat-sen University in Guangzhou she returned to Yunnan to begin her PhD studies at Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, under the supervision of tropical ecologist, Dr Charles H Cannon.

There she obtained a PhD in ecological economics, becoming the first Dai woman from Xishuangbanna ever to earn a doctorate. Her dissertation was concerned with how the prefecture could promote more environmentally and economically conscious practices in its rubber industry.

GoKunming spoke to Yi about southern Yunnan's rubber plantations and her work at the Kunming Institute of Botany. We discussed how a simple sap is transforming the landscape and the lives of many while simultaneously threatening both Dai culture and Xishuangbanna's biodiversity.

GK: When did people begin to grow rubber as a cash crop in southern Yunnan?

Yi: It's been happening since the mid-1950s when there was an American embargo on natural rubber. State farms started planting rubber and taking over valley floors in Xishuangbanna. Things really began to accelerate in 1996 and 1997.

Local governments in Xishuangbanna created programs where they provided smallholders with training on how to switch from traditional crops to rubber. People were also given subsidies — sometimes up to 50 percent of total costs — as well as tree saplings and then taught how to tap them.

Trees take between five and seven years to reach a point where they can be tapped. By 2006 worldwide rubber prices were rising and people who had made the switch to rubber were making noticeably more money than those who hadn't.

More and more people got into it. In the spring of 2011 rubber was selling for the highest prices in history. Smallholders with rubber plantations covering five to six hectares were making 200,000 yuan [US$35,000 at the time] a year — much more money than your average Yunnan farmer.

GK: So in general farming rubber has become an incredibly profitable part of the region's economy?

Yi: It has, but the entire system is inefficient and certain policies actually hurt smallholders financially.

When the government subsidizes rubber planting, they usually don't track where the farmers are going to plant. Globally, Xishuangbanna is on the northern edge of the tropical zone, which does not have the best temperature-humidity ratio to allow plantations to be as productive as they should.

We found if a plantation is higher than 900 meters above sea level and the land's slope is greater than 24 degrees it is not productive at all. Farmers often don't find this out until ten years and a huge investment later.

GK: So some plantations are almost useless. What are the effects on the local ecosystems?

Yi: What it means is we lose all the ecosystem services from the land without any financial return. It is definitely a lose-lose situation. If the original forest was still standing, people might be able to collect mushrooms, find edible insects, plants and animals. The forest also conserves and purifies water, produces oxygen and absorbs carbon dioxide. After clearing land and planting cash crops, all of the benefits and "services" provided by the forest are lost.

Another problem that exacerbates the situation is that Xishuangbanna currently has 95 rubber producing facilities when our research shows it only needs about 30. The farmers don't trust industry latex buyers to give them a fair price and the buyers worry that what they are buying is not as pure as it could be.

The solution to this has been for farmers to treat the latex with chemicals that bind it into a solid cube. Then it sits for a month until a new price is negotiated. When it remains in storage for too long before it is processed a complicated chemical process begins that leads to the rubber degrading in purity. In the end Xishaungbanna rubber is not of a particularly high quality, which causes economic losses for farmers and factories.

The growth of Xishuangbanna's rubber industry, with plantations in orange

GK: So the smallholders and the buyers have a type of mutually reinforced self-fulfilling prophecy?

Yi: Right. And the problems don't stop after the rubber is sold. Processing rubber is a pretty intense operation. It involves the use of powerful alkalines and acids. Those chemicals can seep into the ground, water and air, causing serious pollution.

GK: Besides toxins released into the environment during processing, are there other side-effects from growing rubber?

Yi: The way plantations and smallholdings are run, rubber trees become a monoculture. This leads to serious habitat loss — especially to mushrooms, other fungi and birds.

When making a new plantation, farmland and forested mountains are cleared entirely of trees and ground cover. After everything is removed and saplings are planted there is nothing to hold topsoil in place. Rains wash the soil downhill into lakes and rivers where it causes water oxygen levels to drop. This kills fish and other aquatic animals.

Another problem is that as farming intensifies on land where topsoil has disappeared, growers have to use more and more fertilizer to keep the trees healthy.

GK: How has the influx of money affected people in Xishuangbanna?

Yi: Many Dai people who have become rich have children who don't attend schools. Education in these areas is all in Chinese, not in native languages. Minority kids cannot really follow the lessons and also don't necessarily respect teachers instructing them in Chinese when they speak a different language at home and with their friends.

Traditionally Dai education was the responsibility of the temples. Children were taught in their own language and were also given an education in Hinayana Buddhism. But this sort of schooling is growing less popular too, because families think the money from rubber farming will last forever and their kids don't need an education.

Basically, you have these kids who don't go to school and so they have no background in traditional Dai culture and no Chinese education either. They have no real connection to China and don't feel they have a connection to being Dai either.

Entire villages used to come out and help families build new houses, but now people simply hire contractors instead. These sorts of situations began about ten years ago, but very few people have studied the effects and no one is offering solutions.

GK: So what recommendations would you make regarding the preservation of Dai culture?

Yi: The environmental problems are fixable. But the loss of community isn't. Neither is the loss of cultural traditions such as forest stewardship. Surveys of Dai communities show that people over the age of 35 are still very much concerned with biodiversity conservation. Children who have grown up with nothing but rubber plantations are usually much less troubled by these sorts of questions. They don't really see the point in safeguarding forests.

We really want to launch a comprehensive environmental education plan aimed specifically at kids in Xishuangbanna. It would help explain indigenous knowledge and wisdom from older generations — elucidate how they cared about nature and understood a bit better than people do today the relationship between nature and humans. We want to spell out what responsibilities children have in shaping their own futures and what the future will look like if people don't slow down and consider the consequences.

It also stresses simple ways smallholders can adjust their growing techniques to make them more effective while also conserving land. Some of these are as simple as learning how to measure slope, pay attention to altitude and avoid planting on slopes with only northern sun exposure.

GK: So it's not all gloom and doom?

Yi: No. There are still options and plenty of things to try. Another program I am involved with, run by CGIAR, is looking into forest transition theories and how other countries are shepherding forest regrowth and how it happens naturally.

We are also looking into smallholder plantations to see if we can find if there is a correlation between population, income, education and concern for the environment. Is there a tipping point when any of those factors trigger people to prioritize conservation, water governance and land use?

In the 1960s, farmers in Xishuangbanna were inter-cropping — planting tea, coffee and rubber in the same fields. Those methods were phased out through a series of state reforms. The practice is slowly being embraced once again on an experimental level but no one knows if it works yet.